Litjs



S. G. WIGELIUS. INTERNAL COMBUSTION ENGINE 0F COMPOUND TYPE.

' APPLICATION FILIED MAR-8.1918.

1,321,690. Patented N v. 11,1919.

In ventar' GUSTAF WIGELIUS, OF GOTTENBOBG, SWEDEN.

INTERNAL-COMBUSTION ENGINE 0F COMPOUND TYPE.

Specification of Letters Patent.

Patented Nov. 11, 1919.

Application filed. March 8, 1918. 5011a] No- 221,216.

To all whom it may concern:

Be it known that I, SvnN GUs'rAF Wren- LIUS, subject of the King of Sweden, reslding at Gottenborg, in the Klngdom of Sweden, have invented certain new and usetul Improvements in lnternal-Combustlon Engines of Compound Type, of wh1ch the following is a specification.

The invention relates to internal combustion engines of the compound type, in which the high pressure piston acts as a valve for the low pressure cylinder, and in which the low pressure piston acts as a pump for scavenging the high pressure cylinder by the two compartments of the low pressure cylinder being put into communication with each other through the high pressure cylinder. Internal combustion engines of this kind are previously known. The object of the invention is generally to increase the efficiency of such engines while maintaining relatively small cylinder volumes. This is obtained by a cycle of operations one feature of which consists in the compression produced in the low pressure cylinder during the last part of the return stroke of the low pressure piston and during the first part of the power stroke of the high pressure piston being carried so far that, when immediately afterward, the two cylinders are put into communication with each other, there prevails a pressure on the low pressure cylinder, which is equal, or nearly so, to the pressure in the high pressure cylinder at the time. This course of operation provides for a continuous expansion Without losses due to momentary variations of pressure. To obtain the best possible efliciency the following expansion is to be carried down to atmospheric pressure, but this would also require relatively large cylinder volumes. According to the present invention a small cylinder volume may be used by so adapting the relative movements of the high and low pressure pistons that the working chamber of the low pressure cylinder is entirely closed up by the returning high pressure piston for a period immediately after the scavenging and before the exhaust, thereby providing an after-expansion in the low pressure cylinder.

Thus, the essential features of the invention consists in the compression of the gases in the low pressure cylinder up to the pressure of the high pressure cylinder at'the m m t of op n ng the communication b tween the cylinders in combination with the provision of an after-expansion in the low pressure cylinder and the maintaining of a pressure above atmospheric pressure during the scavenging period so as to obtain eflective work out of the low pressure cylinder during the after-expansion.-

V A construction according to the invention is shown in the accompanying drawing in which- Figures 1, 2 and 3 show three positions of the pistons.

Another construction is shown in Figs. 4, 5 and 6;

For the sake of clearness, all the parts have, in the drawing, been placed in the same plane, although, in reality, the execution is different.

a is the high pressure cylinder, 6 the high pressure piston, c the low pressure cylinder, and d the low pressure piston. is the airvalve of the high pressure cylinder chamber, f an inlet valve for fresh air to the chamber under the low pressure piston, and g an outlet valve from the said chamber. h is a channel connecting the two chambers, in which chambers there are arranged the valves 6 and g. c is a feeding valve for fuel, or for fuel and air.

The two cylinder chambers are in connection with each other by means of a port is in the wall between them, which port is so situated that those parts of the cylinder chambers that lie above the piston, come into communication with each other during the downward stroke of the high pressure piston b, at or approximately at, the same instant that the low pressure piston d turns in its upper position when the pressure in the cylinders are equal, or almost so. On the other hand, the port 70 is so situated that a ring-shaped slot Z in the high pressure piston b keeps the low pressure piston in connection with the outlet on during the greater part of the up-stroke of the low pressure piston rod, during which the blowing out takes place. The high pressure piston, during its down stroke, cuts off, however, the connection between the low pressure cylinder and outlet m by closing the opening 70 shown in the position illustrated in Fig. 2, after which compression takes place in the low pressure cylinder, During the continued downward stroke of the high pressure piston, and the up-Jstroke of the low pressu pi ton, the pressu in t e low pres sure cylinder rises:untildt reaches the same,

i .or approximately the same, value as the pressure in the high .pressurecylinder, and

the pistons are in the position shown in Fig, 3, when the communlcatlon between the two cylinders is brought about on the continued down stroke of 'the highpressurepiston and the expansion takes place in both cylinders simultaneously.

"In order teobtaintheinost suitable-co operation between the low pressure cylinder,

on-the-one hand, and tllQ'Olltlt, orthe high V way by its ow ncrank the relativeangleof the pistons to each other ought',cconsequently-,"

tobe. greater than 90 butless than'l80- preferably llO g By this means there isobtained another advantage,viz., that the low-pressure cylinder during the latter part of its down stroke, when the high pressure piston has already turned and is movinggupward, sucks in scavenging air preferably introduced with a little over pressure, through the 'valvee, whereby an effective scavenging'of the high pressure cylinder is obtained.

As, when-'the-high pressure piston bmov'es upward, the low' pressure piston d, which is larger, moves downward, and' as the velocity of the last mentioned piston is I considerably greater atthat* instant, the inv inder.

crease in volumein thelow pressure cyl-f inder is many times greater than the de crease in volume in the high pressure-cyh The scavenging "therefore continues during the continued iupward movement-of the; high pressure piston' b'until'this piston has covered i'thek port 7 after which compression takes place inthe high pressure cylinder chamber: until combustion beginszj When this highpressure piston on moving up Ward covers the poet, the low-pressure oyl inder is atifirst entirelyi closed and as *the low pressurei piston I is 'then I still moving downward, a; further expansion nowtakes lace-.111 thelOW pressure cylinder; This expansion continues until thevhigh pressure piston again uncovers theportflc 'when the low pressure cylinder is put in communication i w-ith'the outlet 1' channel As is seen by: the above description, the

high pressurecylinder chamber I never 20011163 into di'rect'scommunication, on any? occasion; wlth the outlet. channel m.

IQ 'Thefscaven-ging air isobtained-,fromvthe chamber under; thepistomd, where;it is compressed: tor a suitable: ,over pressure-,-, after which-it is carried, during the scavenging period, through the channel It and the valve 0. into" the-high pressure cylinder. In consequence of the inletand outlet ports for the scavenging air lying at opposite ends of the high pressure cylinder chamber, there is obtained aspecially effective scavenging. The

scavenging period does not begin, of course, until the pressurein the low pressure cyl= inde'r-has fallen below the pressure of the scavenging air on the valve chamber of the valve 6.

In the embodiment shown in Figs. 4-6, the valves 7 and g are arranged inthe upper part Of thelOW pressure cylinder, and the port 70 in the lower part of the same. The function is the same asthat in the embodiment: accordingto Figs; 1-3. The rate of speedofthe movements of-the respective pistons is, however, altered, as, in thisform of construction, the 10w pressure piston turns-before the high-pressure piston instead of after it, as in Figs. 1-3.

In theembodiment according to Figs. 4.'6t the'crank' angle isif ordinary crank movement is-employed -180 greater than in the embodiment according to Figs. 1-3, 2'. 6., if, in Figs 1-3 the: high pressure crank goes 110 before the low pressure crank, the high pressure crank in" Figs. 4-6 goes 290" before the'lowpressure crank, or, otherwise expressed, 70 after-the same.

The advantage. of the embodiment'according to Figs. i=6 is that the: channel-5 h is considerably. shorterv than in the embodiment according to Figs. 13.

Method of working internal combustion engines o-fthe compound'type, inwhich the high pressure piston acts: as a valve for the low pressure cylinder, consisting in compressing the gases in thelow pressure piston duringthelastpart of thereturnstroke of thelowpressure piston andduring the first part of. the power stroke ofthe high pressure piston; carrying said compression so far that when, immediately afterward the two cylinders are-put into communication with each other, thereprevails a pressure-in the lowpressure cylinder, which is equal,'or

.nearly so, to the pressure in the high pres sure-cylinder at the time; producing an expansion ofthe combustion gases in botlr cylinders, scavenging the high pressure cylinderrbyputting the two compartmentsv of the. low pressure cylinder intocommunicationwith each otherthrough the-high pressure cylinder; maintaining a. pressure above the atmosphere in both cylinders duringvthe scavenging -goperation=; closing the. working chamber of the low pressure cylinder by the-returning high pressure piston, while the low'pressure piston-is still moving outward, producing; an ezqoansiou in said chamher, connecting said chamber with the eX- sure cylinder is started and the cycle of ophaust port through an opening in the high erations is repeated. 10 pressure piston, and maintaining the ex- In testimony whereof I afliX my signature haust from the low pressure cylinder until in presence of tWo Witnesses.

the high pressure piston after having per- SVEN GUSTAF WIGELIUS. formed part of its power stroke again Witnesses:

closes the lOW pressure cylinder, at which ALFRED ANDERSSON,

moment the compression in the low pres- GUSTAF SANDBERG.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

